<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            background-image: url("../../images/bg-gongxueyuan.jpeg");
        }

        .btn-div {
            width: 500px;
            position: absolute;
            left: 50%;
            transform: translateX(-50%);
        }

        .content-div {
            width: 500px;
            position: absolute;
            top: 50px;
            left: 50%;
            transform: translateX(-50%);
            background-color: red;
            color: white;
            padding: 5px;
        }

        #btn-01 {
            background-color: red;
            height: 15px;
            width: 20px;
        }

        #btn-02 {
            background-color: green;
            height: 15px;
            width: 20px;
        }

        #btn-03 {
            background-color: blue;
            height: 15px;
            width: 20px;
        }

        .video-class {
            position: absolute;
            top: 300px;
            left: 50%;
            transform: translateX(-50%);
        }
    </style>
</head>

<body>
    <div class="btn-div">
        <button id="btn-01"> </button>
        <button id="btn-02"> </button>
        <button id="btn-03"> </button>
    </div>
    <div id="content-id" class="content-div">
        <div>什么是 HTML？</div>
        <div>
            HTML 是用来描述网页的一种语言。
            HTML 指的是超文本标记语言 (Hyper Text Markup Language)
            HTML 不是一种编程语言，而是一种标记语言 (markup language)
            标记语言是一套标记标签 (markup tag)
            HTML 使用标记标签来描述网页
            <p>
                <a href="https://www.situ.edu.cn/" style="color: white;">欢迎访问沈工网站！</a>
            </p>
        </div>
    </div>
    <video width="800" class="video-class" controls>
        <source src="../../images/1.4.1.mp4" type="video/mp4">
    </video>
</body>

</html>